1. Field of the Invention
The present invention relates to a reciprocating compressor and a refrigerator having the same, and more particularly, to a reciprocating compressor capable of simplifying components by two-stage compressing a refrigerant by using one reciprocating motor, capable of being easily controlled, and capable of compressing a refrigerant with a high pressure ratio and a decreased load, and a refrigerator having the same.
2. Description of the Conventional Art
Generally, a compressor is a device for compressing a refrigerant by converting electric energy into mechanical energy. The compressor is part of a refrigerating cycle system, and the refrigerating system is utilized in a refrigerator, an air conditioner, a show case, etc.
The compressor is classified as a rotary compressor, a reciprocating compressor, a scroll compressor, etc. according to a mechanism for compressing a refrigerant. As a compressor that is part of the refrigerating cycle system mounted in a refrigerator, a reciprocating compressor is mainly used.
It is possible that the refrigerator is provided with one evaporator and cool air generated from the evaporator is circulated into a freezing chamber and a refrigerating chamber. It is also possible that the refrigerator is provided with two evaporators and cool air generated from the respective evaporators is respectively circulated into the freezing chamber and the refrigerating chamber. According to the type of the refrigerator, a type of a reciprocating compressor mounted at the refrigerator is varied.
FIG. 1 is a sectional view showing an example of a reciprocating compressor.
As shown, the reciprocating compressor comprises a casing 100 having two suction pipes 101 and 102 and one discharge pipe 103, a frame unit 110 provided with one cylinder hole C1 having a certain inner diameter and mounted in the casing 100, first and second reciprocating motors facing each other at both sides of the frame unit 110 for generating a linear-reciprocation force, a first piston portion 140 inserted into the cylinder hole C1 and connected to a mover 121 of the first reciprocating motor, a second piston portion 150 inserted into the cylinder hole C1 to face the first piston portion and connected to a mover 131 of the second reciprocating motor 130, a first resonant spring unit 160 for elastically supporting the first piston portion 140 and causing a resonant motion, a second resonant spring unit 170 for elastically supporting the second piston portion 150 and causing a resonant motion, suction valves 181 and 182 respectively coupled to ends of the first and second piston portions 140 and 150 for opening and closing a suction flow path formed in the piston, and a discharge valve 183 for opening and closing a discharge channel connected to the discharge pipe 103.
The suction pipes 102 and 103 are symmetrically positioned at both sides of the casing 100.
The discharge pipe 103 is coupled to the frame unit 110 so as to be connected to a compression space P1 formed in the cylinder hole C1 by the first and second piston portions 140 and 150.
The first and second reciprocating motors 120 and 130 are equally (i.e. substantially identically) formed, and comprises inner stators 122 and 132 and outer stators 123 and 133 coupled to the frame unit 110 with a certain there between, and movers 121 and 131 movably coupled between the inner stators 122 and 132 and the outer stators 123 and 133 for transmitting a driving force of the motor to the piston.
The first and second resonant spring units 160 and 170 are equally formed, and comprises spring supporters 161 and 171 coupled to the pistons, and springs 162 and 172 positioned at both sides of the spring supporters 161 and 171.
An operation of the reciprocating compressor will be explained.
When a power is applied to the reciprocating motor, the movers 121 and 131 of the first and second reciprocating motors 120 and 130 are linearly reciprocated in opposite directions and the linear-reciprocation of the movers 121 and 131 are respectively transmitted to the first and second piston portions 140 and 150. Accordingly, the first and second piston portions 140 and 150 are linearly-reciprocated in the cylinder hole C1 in opposite directions. As the result, a refrigerant respectively sucked through the suction pipes 101 and 102 is sucked into the compression space P1 inside the cylinder hole C1 through suction flow paths 141 and 151 formed at the first piston portion 140 and the second piston portion 150, compressed, and discharged.
That is, when the first and second piston portions 140 and 150 move towards the outside the cylinder hole C1, a pressure of the compression space P1 formed by the first and second piston portions 140 and 150 and the cylinder hole C1 is lowered and the suction valves are respectively opened. Then, a refrigerant respectively sucked through the suction pipes 101 and 102 is sucked into the compression space P1 through the suction flow paths 141 and 151 of the first piston portion and the second piston portion.
When the first and second piston portions 140 and 150 move towards an inner side of the cylinder hole C1, the compression space P1 has a varied volume thereby to compress the refrigerant. Also, when the refrigerant has a pressure more than a set pressure, the discharge valve 183 is opened and the compressed refrigerant is discharged.
The reciprocating compressor individually controls two reciprocating motors and controls strokes of the pistons, thereby controlling a compression capacity of the refrigerant. Also, since the reciprocating motors are arranged to face each other, a vibration can be attenuated.
However, since the reciprocating compressor has two reciprocating motors and two components, a fabrication cost of the reciprocating compressor is expensive.
FIG. 2 is a sectional view showing another example of the reciprocating compressor.
As shown, the reciprocating compressor comprises a casing 200 having one suction pipe 201 and two discharge pipes 202 and 203, a frame unit 210 elastically supported in the casing 200, first and second cylinders 220 and 230 fixedly coupled to both sides of the frame unit 210, a reciprocating motor 240 mounted at the frame unit 210 for generating a linear-reciprocation force, a double piston 250 having both sides respectively inserted into the first and second cylinders 220 and 230 and linearly-reciprocated by receiving a driving force of the reciprocating motor 240, suction valves 261 and 262 respectively mounted at both ends of the double piston 250 for opening and closing a suction flow path F1 penetratingly-formed in the double piston 250, discharge covers 263 and 264 for covering the first and second cylinders 220 and 230, discharge valves 265 and 266 inserted into the discharge covers 263 and 264 for opening and closing compression spaces P2 and P3 of the first and second cylinders 220 and 230, and a resonant spring unit 270 for elastically supporting the double piston 250 and causing a resonant motion.
The two discharge pipes 202 and 203 are respectively connected to the discharge covers 263 and 264.
The reciprocating motor 240 comprises an inner stator 241, an outer stator 242 respectively fixedly coupled to the frame unit 210, and a mover 243 positioned between the inner stator 241 and the outer stator 242. The mover 243 is coupled to the double piston 250.
The resonant spring unit 270 comprises a supporter 271 coupled to the double piston 250, and resonant springs 272 positioned at both sides of the spring supporter 271.
Reference numerals 267 and 268 denote valve springs.
An operation of the reciprocating compressor will be explained.
When a power is applied to the reciprocating motor, the mover 243 is linearly reciprocated by the reciprocating motor 240 and the linear-reciprocation of the mover 243 is transmitted to the double piston 250 thereby to linearly-reciprocate the double piston 250. As the double piston 250 is linearly-reciprocated, a compression space P2 of a first cylinder and a compression space P3 of a second cylinder alternately suck a refrigerant, compress and then discharge the refrigerant.
That is, when the double piston 250 moves towards the first cylinder 220, a refrigerant sucked into the first cylinder 220 is compressed. Then, when the refrigerant has a pressure more than a set pressure, the discharge valve 265 blocking the compression space P2 of the first cylinder is opened thereby to discharge the compresses refrigerant. At the same time, the refrigerant is sucked into the compression space P3 of the second cylinder. Also, when the double piston 250 moves towards the second cylinder 230, the refrigerant is sucked into the compression space P3 of the second cylinder 230 is compressed. Then, when the refrigerant has a pressure more than a set pressure, the discharge valve 266 blocking the compression space P3 of the second cylinder is opened thereby to discharge the compresses refrigerant.
The reciprocating compressor is provided with one reciprocating motor 240 thereby to have a cheap fabrication cost. Also, as the refrigerant is compressed by the two cylinders 220 and 230, a compression capacity of the reciprocating compressor is increased. However, when the double piston 250 moves towards one of the first and second cylinders 220 and 230, a collision between components is generated at the side towards which the double piston 250 moves, and a compression is not smoothly performed in the other side. Accordingly, a stroke of the double piston 250 is not easily controlled.
When the reciprocating compressors are mounted in a refrigerator, the reciprocating compressors compress a refrigerant only one time thereby to have a limitation in compressing the refrigerant with a high pressure ratio. Especially, in case of a refrigerator having a freezing chamber side evaporator and a refrigerating chamber side evaporator, a pressure of a refrigerant that has passed through the freezing chamber side evaporator becomes relatively low. When the refrigerant having a low pressure is compressed to have a proper pressure, a load of the compressor is increased thereby to degrade an efficiency of the compressor.